Tube plugging apparatus



B. C. HAWKE TUBE PLUGGING APPARATUS 2 Sheets-Sheet l Zzzyazztr 54574 C MNA/5 .fifi L July 30, 1968 Filed Sept. 19, 1,966

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July 30, 1968 B. c. HAWKE TUBE PLUGGING APPARATUS 2 Sheets-Sheet 2 Filed Sept. 19, 1966 Err As/L C /wgi lll Cfll lllllllll/IIIIIIII United States Patent O 3,394,442 TUBE PLUGGING APPARATUS Basil C. Hawke, San Diego, Calif., assigner, by mesne assignments, to Gulf General Atomic Incorporated, San Diego, Calif., a corporation of Delaware Filed Sept. 19, 1966, Ser. No. 580,438 9 Claims. (Cl. 29-33) This invention relates generally to apparatus for performing certain operations at the ends of tubes in a heat exchanger. More particularly, it relates to apparatus for repairing heat exchangers by detecting and plugging defective heat exchanger tubes.

Many heat exchanger designs, including numerous steam generator designs, utilize a plurality of substantially parallel tubes (which may be straight, U-shaped, etc.) through which a rst uid is passed. A second uid is passed over the exterior of the tubes through the spaces between the tubes, and a transfer of heat occurs between the first and second fluids. In the case of steam generation, for example, Water or 4steam may be passed through the tubes of the heat exchanger while hot gases produced from combustion or from nuclear reaction are passed over the outside of the tubes. The hot gases serve to vaporize the water into steam or, in the case where steam is originally present, serve to superheat the steam.

A heat exchanger configuration frequently utilized is known as the tube sheet type of heat exchanger. In this type of heat exchanger, the tubes terminate at each end in a plane or sheet which comprises one wall of a fluid chamber for supplying fluid to be heated to the tubes or for receiving iiuid which has been heated from the tubes. Often, the tubes are arranged in rows of varying length such that the array of tube ends lies within the boundaries of a circle in the plane of the tube sheet. The ends of the tubes communicate with the fluid chamber which may be at either the high pressure or low pressure ends of the tubes depending upon whether the chamber is for supplying fluid to the tubes or receiving fluid from the tubes. A conduit connects with the chamber for conducting fluid to or from the chamber. In some steam generator designs, the conduit is connected directly to the tube sheet so that the end of the conduit adjacent the tube sheet constitutes the chamber.

In a heat exchanger, tube failure may occur from rupture of a tube such that the hot fluid outside the tubes will contaminate the uid in the tubes, or that the fluid in the tubes will leak out into the surrounding environment. In either case, the usual way of repairing the heat exchanger is to plug the defective tube at both ends so that it is effectively removed from the system. Generally, a heat exchanger will be designed to have several more tubes than is needed for the desired heat exchange capacity to allow for just such a contingency. Repairing the heat exchanger in this manner is far less expensive than disassembling the heat exchanger to replace the defective tube.

In order for a worker to gain access to the tube ends for detecting and plugging defective tubes by conventional hand-operated tools, a large portion Aof the apparatus associated with the heat exchanger (e.g., the fluid chamber and conduit) must usually be disassembled and removed. Furthermore, it is usually necessary to wait until the apparatus cools to tolerable temperatures, and, in the lcase of nuclear apparatus, decontamination may be necessary. All this leads to considerable shut-down time with a consequent economic loss.

It is an object of this invention to provide improved apparatus for repairing heat exchangers.

Another object of the invention is to provide apparatus for remotely performing operations at the ends of tubes in a heat exchanger.

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Still another object of the invention is to provide means for effecting detection and plugging of defective heat exchanger tubes in a hostile environment.

A further object of the invention is to provide means for effecting detection and plugging of defective heat eX- changer tubes without necessitating disassembly of associated apparatus for access to the tubes.

A still further object ofthe invention is to provide apparatus for performing operations at the ends of tubes in a heat exchanger, which apparatus is operable automatically by remote control.

Other objects and the various advantages of the invention will become apparent to those skilled in the art from the following description taken in connection with the accompanying drawings wherein:

FIGURE 1 is an elevational view, partially in section, of apparatus constructed in accordance with the invention and wherein a portion of a heat exchanger and associated elements are shown in phantom;

FIGURE 2 is an end View of a portion of a heat exchanger in connection with which the invention is utilized;

FIGURE 3 is a full section elevational view of a portion of one of a plurality of tools used in the apparatus of the invention;

FIGURE 4 is an elevational view, partially in section, of a further embodiment of the invention;

FIGURE 5 is an enlarged sectional view of a portion of the apparatus of FIGURE 4; and

FIGURE 6 is `an end view taken along the line 6-6 of FIGURE 5.

The invention provides apparatus for performing operations at the ends of tubes in a heat exchanger. The apparatus includes a rotary turret 11 carrying a plurality of extensible tools 12 which, when extended, are adap-ted to engage the ends of the tubes of the heat exchanger. Means 13 are provided supporting the turret in an attude such that the extensible tools are successively alignable with the tubes in the heat exchanger. The turret is rotatable with respect to the supporting rneans by a motor 41. Further means 58, 59 and 61 are provided for displacing the supporting means 13 with respect to the tubes in the heat exchanger so that the extensible tools may be aligned successively with any one of the tubes in the heat exchanger by operating the `displacing means and the motor 41.

Referring in more detail to FIGURE l, the machine illustrated therein is for use in connection with a tube sheet type yof steam generator used in a gas-cooled nuclear reactor. The machine functions to -detect a faulty tube, prepares the end of the tube for welding, inserts a plug in the end of the tufbe, welds the plug to the end of the tube, and nally rechecks the tube for leaks. All operations are remote cont-rolled so that it is unnecessary for an operator to be near the ends of the tube sheet. This means that the tubes may be repaired in a hostile environment, such as an environment of high temperature or high radioactivity. In FIGURE l, the inner surface of a steam conduit is indicated by the phantom lines 14. The apparatus includes a housing 16 comprising a cylindrical body 17 of a diameter slightly smaller than the inner diameter of the steam conduit 14. The housing 16 inserts into the steam conduit from an access port at the opposite end of the conduit from the tube sheet. The face of the tube sheet is indicated lby the phantom line 18, and the tubes therein are indicated at 2i).

The rearward end of the cylindrical body 17 of the housing 16 terminates in an outwardly extending ange 19. The ange 19 is used to secure the housing in the access port of the conduit. A back bearing plate 21 is positioned at the open end of the cylindrical body 17 and is secu-red to the flange 19. Securing of the plate 21 to the flange 19 may be accomplished by means of a plurality of bolts extending around the periphery of the back plate 21, by welding, or by other suitable means. A plurality of guide wheels 22, supported by `arms 23, are distributed at appropriate supporting points about the periphery of the cylindrical body 17 at the end thereof toward the tube sheet 18. These wheels 22 facilitate the insertion of the housing 16 into the steam conduit 14. Once the housing is positioned `as desired, it may be locked into position in the steam conduit 14 by actuating .a plurality of radially extending pneumatic pistons 24 which extend from respective piston housings 26 distributed about the periphery of the cylindrical body 17.

The plurality of tools 12 for performing various operations on the ends of the tubes in the tube sheet are disposed in spaced relation to each other about the periphery of the face of the circular turret 11. A shaft housing portion 27 extends axially of the turret on the opposite side thereof from the tools 12 and provides support for the turret on a turret shaft 28. The turret shaft 28 is rotatably supported by a pair of sapced bearings 29 in a bearing housing portion 31 which extends from the front plate 32 of the saddle 13. Further details of the saddle 13 will be subsequently described.

A turret shaft gear 33 is secured on the end of the turret shaft 28 opposite the turret 11 in order to rotate the turret and turret shaft. The turret shaft gear 33 is driven by a drive gear 34 which is mounted on and driven by a drive shaft 36. T-he end of the drive shaft 36 is journalled in the front plate 32 of the saddle 13 by a bearing 37. The opposite end of the drive shaft 36 is journalled in the back plate 38 of the saddle and is driven, through a Geneva mechanism 39, by a reversible drive motor 41. The Geneva mechanism 39 provides incremental indexing of the turret for reasons to be subsequently explained.

The tools 12 arranged around the periphery of one face of the turret 11 are for performing the various operations necessary to detect and plug a defective tube. A defective tube can cause faulty operation of the heat exchanger. For example, in one type of gasacooled nuclear reactor, the tubes in the tube sheet carry steam and hot helium is passed over the exterior of the tubes in the tube sheet. In such a reactor, a defective tube may permit the hot helium and a certain amount -of radioactivity to escape into the steam-water system, or may permit water or steam to enter the helium ow and possibly damage the helium circulators or the reactor core. Tools have heretof-ore been developed which are capable of detecting leaks in heat exchanger tubes in such reactors. Such tools operate after the Water and steam have been drained from the system by detecting the presence of the helium coolant in the tube. One of the tools 12 is capable of perfor-ming this function. Another tool or tools on the turret 11 are utilized to prepare the end of the faulty tube for welding. Such a tool, for example, may comprise a counterboring tool for removing the old weld between the tube and the wall of the chamber and forming an enlarged opening for a plug.

As previously mentioned, repair of the heat exchanger is effected by plugging the faulty tube. Most heat exchangers have more than the minimum number of tubes required in the system to allow for a certain number of tubes to be repaired in this manner. One of the tools 12 on the turret is designed to insert a metal plug in the end of the defective tube, or in the opening formed by the counterboring weld preparation tool. This tool may carry only a single plug (in most cases it is unlikely more than one tube is faulty), or may have a magazine by -which it can carry several plugs for insertion. Another tool on the turret is provided to effect welding of the plug to the end of the faulty tube. A second detecting tool may be provided, or the original detecting tool may be used to check to insure that the plugging has been properly accomplished.

By way of example, FIGURE 3 illustrates the head of a welding tool. The head includes a body 42 of stepped diameters having an end cap 43 suitably secured thereto. The end cap 43 includes three projecting axially aligned cylindrical portions 44 and a diagonal recess 45 is provided therein. A tool tip 46 extends from the outermost one of the cylindrical portions 44. A welding device 48 is disposed in the diagonal recess 4S, and suitable passages 47 are provided in the body 42 of the tool head to conduct gas to the welding device 48. The welding device 43 shown is for heliarc fusion welding and includes a welding tip 49. The welding tip provides an electric are for heating and fusing the material of the plug and the tube, with the helium gas supplied forming a helium environment for the arc. The tool tip 46 inserts in a recess of the plug 51 in the tube 52 under repair and holds the welding tip 49 in position adjacent the periphery of the plug 51 and the tube 52. The body of the welding tool is rotatably mounted in the turret 11 and is coupled by a suitable drive system (not shown) to a motor. The welding tool and the Weld preparation tool motors are mounted behind the tools and are contained in housings 40. lVhen the welding tool is rotated after engaging the plug, the welding tip 49 is passed about the periphery of the plug 51 to weld same to the tube 52.

The welding tool and the other tools are extensible in order to move into engagement with the tubes in the tube sheet. This is accomplished by means of a pneumatic device having a piston to which the tool is attached. The pneumatic devices are contained in the housings 40 for each tool. As may be seen in FIGURE l, the various conduits 53, which are necessary to carry the electric current and compressed air to the driving motors for the weld and weld preparation tools and to the pneumatic devices for extending the tools, are passed out through an opening in the drive shaft 28. These conduits may then be carried back through the apparatus and the back plate 38. The turret upon which the tools are mounted is returned by rotation in the opposite direction to its original position after each repair cycle to prevent the conduits 53 from becoming excessively twisted.

In order to permit orientation of the turret 11 and the tools thereon with any one of the tubes in the tube sheet 18, the saddle 13 is constructed to move the entire turret 11 with respect to the tubes in the heat exchanger. This is accomplished by providing for rotation of the front plate 32 of the saddle 13 about an axis which is displaced from the axis of rotation of the turret 11. In the apparatus shown in FIGURE l, the saddle includes a cylindrical body S4 which supports the front plate 32 and the back plate 38. The front and back plates of the saddle are secured to an-ges 50 and 55, respectively, on the ends of the cylindrical body 54. The front plate 32, the back plate 38, and the cylindrical body 54 form a rigid structure which is supported for rotation in the housing 16 by means of bearings 56 and 57, at opposite ends of the saddle. Bearing 57 is positioned between the front plate 32 of the saddle and the front edge of the cylindrical body 17 of the housing 16 and abuts the face of the flange 50. Bearing 56 is supported between the periphery of the back plate 38 of the saddle and the back bearing plate 21 of the housing.

For the purpose of rotating the saddle 13 about its axis, which axis is coincident with the axis of rotation of the shaft 36, a drive gear 58 is provided attached to the back plate 38. Drive gear 58 is driven through a gear mechanism, not shown, enclosed in a gear mechanism housing 59, by means of an electric motor 61. Suitable electronic position transmitters or encoders 62 are provided attached to the gear mechanism enclosed in housing 59 in order to remotely correlate the movement of each of the two rotary elements, namely, the saddle 13 and the turret 11, in order to establish or predeterminc the position of the operating tools 12.

In operating the apparatus, the motors 41 and 61 are actuated to traverse the detecting tool across each row of tube ends in the face of the tube sheet (see FIG- URE 2). This may be done either in a predetermined programmed scanning pattern by an electronic control system 60, or by an operator through visual observation of a suitable indicator (not shown) operated from the position transmitter 62. In the event of a faulty tube, the presence of heat exchange fluid I(e.fg., helium) in the tube will be detected by the detecting tool. Upon such detection, the motor 61 will stop the apparatus at that position. This may be accomplished, for example, through automatic means or by the operator acting in response to a'visual indication. The motor 41 is then operated to rotate the turret 11 such that the tool for performing the next succeeding operation is brought into position at the mouth of the faulty tube. The tool then extends into engagement with the mouth of the tube and performs the particular operation to which it is adapted. Upon completion of this operation, the tool is retracted and the turret rotated to the next position so that the next tool is properly aligned with the faulty tube. When the plug has been inserted and welded in place, the turret is rotated back to its original position so the detecting tool returns to alignment with the tube in order to determine if the weld is effective. If the weld is effective, the motor 61 is reactivated to move the detecting head to the next tube in the tube sheet. Alignment of the turret of the machine with each tube is accomplished by means external to and remote from the tube sheet face such that the apparatus is completely independent of the tube sheet.

A further embodiment of the invention, also for use in connection with a steam generator, of the tube-sheet type is illustrated in FIGURES 4 through 6. This embodiment includes a housin-g 63 which inserts in the interior of a steam or water conduit 65 as did the housing 16 of the previous embodiment. The housing 63 includes a cylindrical body 64 and is connected to a cylindrical rear housing 66 by a frame comprised of four divergent struts 131. The struts of the frame are secured to the housing 63 by brackets 132 and to the housing 66 by a ball joint 141. The housing 66 may be filled with shielding 67 in order to prevent radiation from passing out of the conduit 65. The forward end of the cylindrical body 64 of thchousing 63 includes an inwardly turned annular ange 68. The rearward end of the housing 66 has an outwardly turned annular flange 126 which may be bolted in place over a port in the steam conduit to secure the housing 66 in a fixed position with respect to the tube sheet of the steam generator.

As was the case with the previous embodiment, a plurality of tools 69 are mounted about the periphery of a rotatable turret 71. The tools 69 are extensible and operate to perform the various operations on a defective tube with which they are alignable. As may be seen in FIGURE 6, the tools are arranged about the periphery of the turret 71. The motors (not shown) for the weld preparation tool and the welding tool are also positioned near the periphery of the turret 71 and are coupled lby a suitable gear mechanism (not shown) to those tools. As was true in the previous embodiment, the tools 69 are extensible by pneumatic devices 133 (see FIGURE 5) contained in suitable wells 85 in the turret. The wells 85 are capped by plugs 72 and lalso contain the drive motors 'for some of the tools.

The turret 71 is annular in configuration and is mounted for rotation by bearings 75 on the forward part 73 of a two part saddle. The saddle includes a rearward part 70 having a ange 74 in which a central recess is provided. A gimble ring 77 is pivotally secured by means of pivot pins 78 in the recess 76. A floating beam 79 is secured to the gimble ring, by means not shown, to be pivotal about an axis normal to the axis of the pins 78. The pivotal mounting of the gimble ring 77 to the floating beam and to the flange 74 constitutes a universal joint to permit the saddle 70, 73 to assume an infinite number of attitudes with respect to the floating beam 79. The opposite end of the floating beam is pivotally mounted in a gimble ring 81. The gimble ring 81 is pivotally mounted, in turn, to a ring 82 which is secured in the flange 68 in fixed position. The mounting of the gimble ring 81 to the floating beam 79 and the fixed ring 82 constitutes a universal joint for the floating beam such -that the beam may assume an infinite number of attitudes with respect to the housing 63.

In order to insure that the tools 69 are properly aligned with the tubes in the -tube face under repair (which may beidentical with that shown in FIGURE 2), the saddle 70, 73 is supported such that its attitude with respect to Athe tube face is always the same. This is accomplished by means of four arms 83 which couple the ilange 74 of the rearward portion 70 of the saddle to the flange 68 of the housing 63. The arms 83 are mounted at 90 to one another around the axis of the beam 79 and provide a four-bar -linkage system which maintains the saddle in an attitude such Ithat the tool face of the turret is parallel with the tube sheet regardless of the position of the saddle. The ends of the arms 83 are supported in ball joints 84 in the saddle ange 74 and in similar ball joints 86 on the housing flange 68. These ball joints permit universal motion of `the arms.

To align the desired tools 69 with any one of the tubes in the tube face, the saddle 70, 73 is moved relative to the tube face by means of the oating beam 79'. This move' ment is accomplished by a traversing mechanism, explained below. Prior to initiation of lthe traversing mechanism, the beam 79 is locked rigidly by suitable means, not shown, t-o facilitate its insertion into the conduit 65. Insertion of the machine is facilitated by the ability of the rear housing yto universally pivot on the ball joint 141. To accurately locate the housing 63 radially in the conduit, the conduit is provided with an annular lip 143. The lip has a beveled edge toward the housing 63 and the housing engages this edge :and is radially located thereby. The lip may be provided with keyways and the housing 63 provided with corresponding keys (neither of which is shown) in order to secure the housing 63 against rotation in the conduit. When the back flange 126 is bolted in place, the turret and saddle assembly is adjacent the tube face. The turret and saddle assembly carries several plungers, explained below, one of Which is extended and located to enter a tube in the tube sheet and thus support the turret and saddle assembly. The locking means for the beam 79 may then be released.

Once the locked beam is inserted and the turret is adjacent the tube face, the traversing mechanism is activated to permit the machine to walk over the tube sheet. The traversing mechanism operates to rotate the saddle 70, 73 and the turret 71 in opposite directions with respect to each other, and comprises a drive shaft 88 which extends through the floating beam 79 and terminates in a pair of ears 89. A gimble ring 91 is pivotally secured between the ears 89, and a drive shaft extension 92. is pivotally secured by a pair of ears 93 to the gimble ring 91. The result of the foregoing construction is a universal joint between the drive shaft extension 92 and the driveshaft 88, which joint permits the shaft extension 92 :to be rotated in response to rotation of the drive shaft 88.

The drive shaft extension 92 is journalled in the rear portion 70 of the saddle by means of two axially spaced ball bearings 94. A suitable shaft passage and gear chamber 96 is provided centrally of the saddle rear portion 70 in order to accommodate the drive shaft extension and a planetary gear mechanism. The drive shaft extension 92 carries a gear 97 Which operates as the sun gear in a planetary gear mechanism. An idler shaft 98 is mounted in bearings 99 .and lcarries a planet gear 101 in engagement with the sun gear 97. The idler shaft 98 carries a fur-ther planet gear 102 which extends through a slot 103 in the wall of the chamber 96. The slot 103 communicates with an annular space 104 of L-shaped cross section between they rearward portion 70 and the foreward portion 73 of the saddle. An annular portion 106 of the turret 7 71 extends into the recess 104 and has an annular gear 107 thereon which mates with the idler gear 102.

In order to accomplish the walking operation previously described, the saddle carries a pair of extensible plungers 108 and 109 which are aligned with the tubes in the tube sheet. The turret also carries an extensible plunger 110, near the periphery thereof, also aligned with the tubes in the tube sheet. Each of the plungers is pneumatically actuable to extend and enter the one of the tubes with which it is aligned. One of the saddle plungers 108 and 109 is extended to enter one of the tu-bes in the tube sheet as the machine is inserted in the conduit. Upon rotation of the drive shaft by means of a suitable drive mechanism 111 carried in the interior of the housing 63, after unlocking the beam 79, the walking will take place. This is because the drive shaft extension 92 will rotate the planetary gear mechanism to produce relative rotation between the saddle and the turret in opposite directions. Since the entire saddle-turret assembly is in a oating type of suspension, the resultant forces will displace the saddle-turret assembly with respect to the tube sheet. Upon a predetermined amount of relative rotation, the turret plunger 110 is extended to enter one of the tubes in the tube sheet and the saddle plunger is withdrawn. The relative rotation is then resumed and the moment of the saddle-turret assembly takes place with respect to the newly inserted plunger. Thus, the turret may be traversed from tube to tube over the entire array of tubes in the tube sheet. The two saddle plungers insure that convenient angular relationships are available to displace the turret and saddle no matter what relation the turret and saddle have to each other.

Another type of walking displacement may be accomplished without using the turret plunger 110. This may be achieved by securing a remotely actuable brake to the idler shaft 98 in the planetary gear mechanism. With the shaft 98 locked, the turret and the saddle will both rotate together with the drive shaft extension 92. Accordingly, the saddle is rotated with respect to the tube sheet, causing the saddle to pivot on the extended one of plungers 108 and 109 and produce the walking action. The plungers 108 and 109 are alternatively extended to continue this action.

The method of traversing the tube sheet may be better understood by referring to FIGURE 2. The tube sheet illustrated therein, although shown only by way of example, is arranged in a triangular pattern within the general outline of a circle. With one plunger extended into the tube to which it has been approximately aligned when the machine is inserted in the conduit 65, one of the other plungers is moved to a position approximately 60 from the inserted plunger. The driving mechanism 111 may be suitably calibrated to produce incremental rotation of the saddle and turret in this manner. With a retracted plunger -aligned with a new hole, it is then inserted into the hole with which it is aligned, the previously extending plunger is retracted, and the sequence repeated as before until one line of tubes has been traversed. Upon reaching the end of a line of tubes, the relative positioning of the plungers is 120 or 180 in order to move the turret from one line of tubes to another. The angle of rotation required will depend upon the location of the rst tube in the succeeding line.

When the detecting tool on the turret 71 has aligned itself with a tube which is defective, and the presence of coolant is detected, a signal will be sent from the detecting tool to a suitable electronic control circuit or to the operator. At this point, the retracted one of plungers 108 and 109 is actuated to insert into the hole with which it is aligned. The plungers 108 and 109 will thereby secure the saddle to the tube face and 4against rotation. The drive mechanism 111 is then activated to rotate the drive shaft 88 and the drive shaft extension 92.

This will cause the gear 97 to rotate, turning the gear 101 and the idler shaft 98, and hence turning the gear 102. Turning of the gear 102 will, since the saddle 73 is xed against rotation with respect to the tube sheet, cause the turret 71 to rotate with respect to the tube sheet by means of the gear 107. Incremental rotation of the turret 71 in this manner will bring the tools 69 successively into alignment with the defective tube for plugging. The plugging operation is accomplished in the same manner as described in connection with the previous embodiment.

Since the oating beam 79 is of xed length, the turretsaddle assembly will move through an arcuate path with its center of curvature at the universal joint in the ange 68. To maintain the plungers 108, 109 and 110, and the tools 69 suiciently close to the face of the tube sheet, the forward position 73 of the saddle is made axially displaceable with respect to the rearward portion 70. The rearward portion 70 is provided with a neck 136 which protrudes through a central coaxial opening in the forward portion 73. The forward portion and the rearward portion are coupled to each other on the neck 136 in a manner to permit relative axial movement but to prevent relative rotation. This may be achieved by a suitable spline coupling, not illustrated. The neck has a cylinder 137 therein in which is disposed a pneumatically actuable piston 138. The piston is biased toward the rearward end of the cylinder by a coil spring 139, and a piston rod 141 protrudes exteriorly of the cylinder to be secured to a cap 112. The cap is bolted or similarly secured to the forward portion 73 of the saddle.

Upon application of pneumatic pressure in the cylinder 137 behind the piston 138 by suitable means, not shown, the position of the piston may be controlled. Since the forward portion 73 of the saddle is secured to the piston through the cap 112 and piston rod 141, the axial position of the forward portion with respect to the rearward portion 70 may be regulated by the application of a suitable amount of pneumatic pressure. The turret 71, being journalled on the forward portion, will move axially with the forward portion. Thus, the plungers 108, 109 and 110, and the tools 69, may be kept the proper distance from the face of the tube sheet irrespective of the position of the floating beam 79.

In order to provide a visual indication of the position of the various tools inthe turret, the apparatus is equipped with a secondary turret 113. This secondary turret is mounted on the end of the drive shaft 88 which passes through a housing 114 containing part of the drive mechanisrn for the shaft 88. The turret 113 carries one contact 121 for each tool and plunger, located in corresponding positions. A scanning screen 123 having an array of contacts 124 thereon coinciding with that of the tube sheet is mounted to the housing 63 in a suitable fashion.

As the turret 71 is traversed over the tube sheet, an indication of tool or plunger position is picked up on the scanning screen 123 as the contacts 121 and 124 engage. Alternatively, a light source and photocell arrangement may be used. In either case, it will be apparent to those skilled in the art that suitable electronic circuitry may readily be devised for providing accurate control of the operating elements of the machine. Thus the machine may be operated completely by remote control.

Although not illustrated herein, the general principles of the invention are applicable to the type of heat exchanger coniguration known as the header type of heat exchanger. In this type of heat exchanger, the tubes terminate at each end in the walls of a cylinder. The tube ends are arranged radially about the cylinder walls and axially along the cylinder walls. iOne end of the cylinder is generally closed, and the other end communicates with the fluid conduit for conducting fluid to or from the cylinder. The cylinder thereby serves as a fluid chamber and may be at either the high pressure or low pressure ends of the tubes.

In this type of heat exchanger, tube failure may also occur and the usual way of effecting repair is to plug the defective tube at both ends so that it is effectively removed from the system. Ditliculties encountered in repairing heat exchangers of this design are similar to those encountered with heat exchangers of the tube-sheet design. In applying the principles of the invention to the header type heat exchanger, the tools are arrayed radially about a rotary turret. The turrent is mounted on a saddle or similar type of device, which device is movable axially within the header in order to successively align the radially extending tools with the various tubes.

It will therefore be seen that the invention provides improved apparatus for performing various operations at the ends of tubes in a heat exchanger. More specifically, the invention provides effective means for detecting and repairing defective heat exchangers in a hostile environment. As a result, it is unnecessary to disassemble the heat exchanger or associated apparatus and the invention is adaptable to operation by remote control. In the first embodiment discussed herein, alignment of the turret of the machine with each tube was accomplished by means external to and remote from the tube sheet. The second embodiment discussed herein employs a method by which the turret is caused to traverse the tube array by utilizing the tubes themselves. In either case, the foregoing discussed objects of the invention are accomplished.

Other embodiments in addition to those shown and described herein will be apparent to those skilled in the art from the foregoing discussion and such other embodiments and modifications thereof are intended to fall within the scope of the appended claims.

What is claimed is:

1. Apparatus for performing operations at the ends of tubes in a heat exchanger, said apparatus including in combination, a rotary turret carrying a plurality of extensible tools for performing various operations at the ends of the tubes in the heat exchanger, means supporting said turret in an attitude such that said extensible tools are successively alignable with the tubes in the heat exchanger, means for rotating said turret with respect to said supporting means, and means for displacing said supporting means with respect to the tubes in the heat exchanger, whereby said extensible tools may be aligned successively with any one of the tubes in the heat exchanger by operating said displacing means and said rotating means.

Z. Apparatus according to claim 1 wherein means are provided for indicating the position of each of said tools with respect to the tubes.

3. Apparatus according to claim 1 wherein a conduit communicates with the ends of the tubes and wherein said supporting means are elongated and are provided with means for guiding said turret through the conduit to a position adjacent the tube ends.

4. Apparatus according to claim 1 wherein said tools are adapted to detect and plug defective tubes in successive operations, wherein a sensing tool is initially aligned with each of the tubes, and wherein electronic means are coupled to said sensing tool for activating said rotating means and for successively activating the other ones of said tools in a predetermined order when said sensing tool indicates a defect.

5. Apparatus according to claim 1 for use on a heat exchanger in which the tubes at their ends are substantially parallel with each other, wherein said supporting means supports said turret in an attitude such that said extensible tools are substantially parallel with the tubes, and wherein said displacing means operates to displace the axis of rotation of said turret.

6. Apparatus according to claim 5 wherein said displacing means comprise an eccentric.

7. Apparatus according to claim 5 wherein said displacing means comprise an angularly displaceable boom.

8. Apparatus according to claim 7 wherein said supporting means include a pair of plungers alternately operable to enter respective ones of the tubes to provide an eccentric pivot point about which said support means may pivot in response to operation of said displacing means, whereby said support means and hence said turret may be walked across the ends of the tubes in the heat exchanger.

9. Apparatus for repairing a heat exchanger, said Iapparatus including in combination, a rotary turret carrying a plurality of extensible tools for performing successive detecting and plugging operations at the ends of the tubes in the heat exc-hanger, elongated means for supporting said turret adjacent the ends of the tubes in an attitude such that said extensible tools are successively alignable with a selected one of the tubes in the heat exchanger upon incremental rotation of said turret, means for rotating said turret in increments with respect to said supporting means, and means for displacing said supporting means and hence said turret with respect to the tubes in the heat exchanger for selecting one of the tubes, said extensible tools thereby being alignable in succession with any one of the tubes in the heat exchanger in accordance with the position of said turret with respect to the tubes.

References Cited UNITED STATES PATENTS 1,289,390 12/1918 Calleson 29--33.8 X 2,378,923 6/1945 Honegger 29-35-5 RICHARD H. EANES, JR., Primary Examiner'.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,394 ,442 July 30 1968 Basil C. Hawke It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 2l, "sapced" should read spaced Column 8, line l5, "position" should read portion Signed and sealed this 20th day of January 1970.

(SEAL) Attest:

Edward M. Fletcher, J r.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR. 

1. APPARATUS FOR PERFORMING OPERATIONS AT THE ENDS OF TUBES IN A HEAT EXCHANGER, SAID APPARATUS INCLUDING IN COMBINATION, A ROTARY TURRET CARRYING A PLURALITY OF EXTENSIBLE TOOLS FOR PERFORMING VARIOUS OPERATIONS AT THE ENDS OF THE TUBES IN THE HEAT EXCHANGER, MEANS SUPPORTING SAID TURRET IN AN ATTITUDE SUCH THAT SAID EXTENSIBLE TOOLS ARE SUCCESSIVELY ALIGNABLE WITH THE TUBES IN THE HEAT EXCHANGER, MEANS FOR ROTATING SAID TURRET WITH RESPECT TO SAID SUPPORTING MEANS, AND MEANS FOR DISPLACING SAID SUPPORTING MEANS WITH RESPECT TO THE TUBES IN THE HEAT EXCHANGER, WHEREBY SAID EXTENSIBLE TOOLS MAY BE ALIGNED SUCCESSIVELY WITH ANY ONE OF THE TUBES IN THE HEAT EXCHANGER BY OPERATING SAID DISPLACING MEANS AND SAID ROTATING MEANS. 